Fair Value Measurements and Derivative Instruments - Recurring (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015
Assets:
Derivative financial instruments		$ 2,180	$ 4,759
Liabilities:
Derivative financial instruments		472,685	914,477
Fair Value, Measurements, Recurring | Level 1
Assets:
Investments	[1],[2]	3,669	3,965
Total Assets	[2]	3,669	3,965
Fair Value, Measurements, Recurring | Level 2
Assets:
Derivative financial instruments	[3],[4]	36,697	134,574
Total Assets	[4]	36,697	134,574
Liabilities:
Derivative financial instruments	[4],[5]	507,202	1,044,292
Total Liabilities	[4]	507,202	1,044,292
Total | Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments	[3]	36,697	134,574
Investments	[1]	3,669	3,965
Total Assets		40,366	138,539
Liabilities:
Derivative financial instruments	[5]	507,202	1,044,292
Total Liabilities		$ 507,202	$ 1,044,292

[1] Consists of exchange-traded equity securities and mutual funds reported within Other assets in our consolidated balance sheets.

[2] Inputs based on quoted prices (unadjusted) in active markets for identical assets or liabilities that we have the ability to access. Valuation of these items does not entail a significant amount of judgment.

[3] Consists of foreign currency forward contracts, interest rate swaps and fuel swaps. Please refer to the “Fair Value of Derivative Instruments” table for breakdown by instrument type.

[4] Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. For foreign currency forward contracts, interest rate swaps, cross currency swaps and fuel swaps, fair value is derived using valuation models that utilize the income valuation approach. These valuation models take into account the contract terms, such as maturity, as well as other inputs, such as foreign exchange rates and curves, fuel types, fuel curves and interest rate yield curves. Fair value for foreign currency collar options is determined by using standard option pricing models with inputs based on the options’ contract terms, such as exercise price and maturity, and readily available public market data, such as foreign exchange curves, foreign exchange volatility levels and discount rates. All derivative instrument fair values take into account the creditworthiness of the counterparty and the Company.

[5] Consists of foreign currency forward contracts, interest rate swaps and fuel swaps. Please refer to the “Fair Value of Derivative Instruments” table for breakdown by instrument type.